Roller-hearth type electric furnace



4 Sheecs'fSheet 1 F. R. J. DAVIS El' AL ROLLER HEARTH TYPE ELEGTRIC FURNACE Filed March `23, T939 June 18, 1940.

INVENTORS R4L Davis and P. L essman ATTORNEY Frederick Gerhard :nllnllllllllllll June 18, 1940. F. R. J. DAVIS Er A1.

R01-LER HEARTH TYPE ELECTRIC .FURNACE 4 Sheets-Sheet 2 Filed MarshV 23, 1.939

v INVENTQRS Fre derk RJ.' Dams 2nd Gerhard I? L essm an ATTORNEY June 18 1940. V I F. RfJ. DAvls Er AL 2,205,242

ROLLER HEARTH TYPE ELECTRIC FURNACE @MKZMM N v ATTORNEY June 18, 1940. F. R. J. DAvls Erm.

` ROLLER HEARTH TYPE ELECTRIC ymamma Filed March 23,.. 1939 4 sheets-sheet 4 INVENTORS- ATTORNEY lfbederc-If RJ. Davis and Geld/1 ard IBZYL essmnn.

Patented June 18, 1940 UNITED STATES PATENT OFFICEvr ROLLER-HEARTH TYPE ELECTRIC FURNACE Frederick R. J. Davis, Irwin, and Gerhard P.

Lessmann, Forest Hills, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsyl-4 vania Application March 23,

26 Claims.

. It is common in the construction of heat treating furnaces to encase the wall structure in an outer metallic shell. Our invention relates to the construction of such a shell, particularly adapted to a furnace of the roller-hearth type, and preferably one in which a protective atmosphere is ernployed to envelope the charge undergoing heattreatment.

v Inasmuch as furnaces of this type vary considerably in lengths, and may reach lengths of 100 feet, or vmuch more, the construction of the outer metallic shell or casing presents quite a problem, particularly if the construction costs of y the shell are to be kept low, and the shell is to be made impervious to gas so that, on the one hand, the protective atmosphere inside the furnace cannot leak out, or, on the other hand, outside air cannot leak into the furnace to contame lnate protective gases therein. The problem is most dicult on the side of the furnace carrying the drive for the rolls since, on this side, known as the drive-side, the ends of the rolls of the roller-hearth protrude for some distance beyond the wall proper Vin order that they may be properly supported and that power-transmitting means for rotating the rolls may be applied thereto. To render this side impervious to gas, it is customary to encase the protruding ends ofthe rolls, the bearings, cooling means, if any, and the power-transmitting means in a channel-like en- ,course, with suitably placed holes or apertures for the reception of theusual furnace appurtenances, as for example, terminal leads, rolls for the roller-hearth, thermostats, peep-holes and the like. Structural steel members were employed on the outside of the shell to reinforce it and correspondingly to permit the use of a lighter gauge sheet for the shell. The channel enclosure for encasing the protruding ends of the roll on,

the drive-side was customarily attached tothe side sheet encasing the wall proper. The attachment of the channel structure to the shell required much cutting and fitting of the metal parts, and an appreciable amount of welding. In furnaces employing a protective gaseous atmosphere, the welding necessarily must be gas-tight,

1939, Serial No. 263,694

and, therefore, executed with care and at con- Nevertheless, in spite of such' siderable expense. precautions, gas leaks frequently develop sothat the prior structures Were not only relatively expensive, but also required continuous inspection and repair.

In accordance with our invention, however, the

`structural reinforcing members are'attached tov the inside of the sheets, that is, on the side to- Ward the interior of the furnace so that theyy do not interfere with the channel structure. `Ad ditionally, we form the channel structure in part by the side sheets themselves. In accordance with our invention, we accomplish this byform` ing the drive-side of the shell of twosections of sheet each bent over at top or bottom, as the case may be, to form the channel, thereby eliminating the welded joints previously necessary in attaching the channel enclosure to the wall4 proper.

We thereby eliminate much of the cutting,

close-fitting, and heavy welding that was pre' viously necessary, but nevertheless obtain a bet-- ter gas-tight channel at a lesser expense, and onerequiring practically no upkeep expenditures.

In some instances, the furnace operation -orthe furnace construction may besuch thatan exceptionally high temperature difference, relative-vv ly, exists between the shell adjacent the brickwork of the furnaceand the outer parts of the drive-side channel. In such cases the elongations vwould be' different and forces tending tol buckle or bow the Whole side'of the shell are cre` ated. This buckling mayv sometimes disrupt the furnace wall. In our novel structure,we provide the channel with specially-formed expansion joints which may be spaced every so often along the length of the channel, and in this way wev prevent the creation of the aforesaid buckling` forces.

Many other of the novel features, objects and accomplishments of our invention will be appar-v ent from the following description thereof taken in conjunction with the'drawings which show the. essential features of our invention but Which pur? posely omit for the sake of clarity many of the common appurtenances that go into a furnace construction, and which do not form an essential part of our invention. n

In the drawings, in which like numerals refer to like parts, y

Fig-ure 1 is a somewhat schematic view'in the transverse section of a roller-hearth furnace ern- .y

bodying our invention; Y y Fig. 2 is an enlarged view from'the outsidev of the inside of the shell;

Fig. 5 is a sectional view taken on the line V-V of Fig. 4 with the cover plate attached;

Fig. 6 is an enlarged view from the outside of the furnace of a portion of the off-drive-side of the shell;

Fig. 7 is a cross-sectional view taken along the line VII-VII of Fig. 6;

Fig. 8 is a cross-sectional'view taken along the line VIII-VIII of Fig, 6;

Fig. 9 is a fragmentary vertical sectional View of a shell and drive-side channel in accordance with a common prior construction;

Fig. is an elevational View of an expansion joint applied to the drive-side channel;

Fig. 11 is a horizontal sectional view taken on the line XI--XI of Fig. 10;

Fig. 12 is a horizontal sectional view taken on the line )UI-Kil of Fig. 10; and

Fig. 13 is a vertical sectional View taken on the line XIII-)GII of Fig. 10`

Referring more particularly to Figure 1, we have shown a roller-hearth furnace comprising a bottom wall 2, an arched top wall 4, a driveside wall 6, and an off-drive-side wall 8 defining a heating chamber IIJ in the interior of the furnace. In accordance with customary practice, the walls are constructed of refractory brick exposed to the heat of the furnace and insulating brick outwardly of the refractory brick. If desired, mineral wool, or the like,. I2 may be employed near the shell (or next to the shell) at the top and sides.

The walls of the furnace are suitably encased in a metallic shell indicated in its entirety by the reference character I4, and the entire furnace is supported upon a suitable foundation Which comprises channel. members I 6 running the length of the furnace, and disposed at each end thereof directly below the exposed sides of the walls 6 and 8.

The portion of the shell on the drive side is indicated in its entirety by the reference numeral I8 and that on the off-drive-side is indi-- cated in its entirety by the reference numeral 2G, and Views of portions of these are shown in greater detail in Figs. 2 and 6, respectively. Inasmuch as our invention is directed primarily to the construction of the side wall portions of the shell, a somewhat detailed description of the drive-side sheet and the oif-drive-side walls will be suicient to enable one skilled in the art to follow the principles of our invention.

Located at a suitable distance above the bottom wall 2, is a roller-hearth 24 comprised of a plurality of rolls 26 extending through suitable openings in the side walls 6 and 8 and in the side shell portions I8 and 20. The rolls may be formed in any 'suitable manner as, for example, of hollow tubes having solid end portions made integral therewith, the end portions being stepped with decreasing diameters for the purpose of providing reasonably sized end shafts that can be supported in suitable bearings.

In the particular construction shown, the

drive-side end of the rolls are supported in bearrings 21, and the oif-drive-side ends are supported by bearings 28. We prefer to make the bearing on the drive-side a xed bearing, while that on the off-drive-side is an expansion bearing to permit expansion and contraction of the rolls when variations in temperature occur. The drive-side ends of the rolls protrude through their supporting bearings so that sprocket wheels 30 may be attached thereto. It is customary with driven rolls that one or more of the rolls protrude outward of the encasing channel and this is shown in Fig. l, it being understood that the other rolls terminate inside the channel, as is well known. Those rolls protruding outward of the channel have packing glands or seals 32 to prevent any protective atmosphere within the furnace from leaking out through the apertures through which the ends of the roll pass.

The ends of the rolls that protrude outward of the channel have a 'second sprocket wheel 34 attached thereto overwhich rides a sprocket chain 36 driven by a suitable power means as, for example, a motor 38 and driving sprocket wheel 46.

It is obvious that the power of the motor will beV transmitted to those rolls having ends protruding through the channel, and that these rolls in turn by means of sprocket chains inside the channel engaging the sprockets on the other rolls as wellV as on the motor-driven rolls, will cause the desired rotation of the roller-hearth.

A chain-guiding channel 42 is disposedinside the larger drive-side channel and below the supports therein for the purpose of guiding the inside sprocket chains, and also catching any lubricant from the oil cup 44 which drips oil upon the power transmitting means inside the driveside channel.

In some furnaces it is necessary to water-cool the bearings supporting the rolls of the rollerhearth and sometimes the rolls themselves are water-cooled. Accordingly the drive-side channel is provided with water inlets 46 and water outlets 48, for conveying water to the parts that require cooling by an appropriate pipe system inside of the drive-side channel and conveying the water out after it had served its purpose.

The foregoing structure has been described only briefly since it follows, in general, prior constructions, but our invention is primarily directed to a manner in which the shell I4 is created, in particular, the drive-side shell portion IB and off-drive-side shell portion 20.

Both of the shell portions I8 and 20 are formed of a plurality of sheets of metal whose number depends upon the length of the furnace. Manifestly, for an exceptionally long furnace the shell portions must be formed of endwise juxtaposed sheets so that the full length can be obtained.

Referring more particularly to the off-driveside portion 26, as shown in Figs. 6, '7 and 8, each sheet 5l) extends the height of the furnace and has suitable apertures 52 through which the ends of the rolls of the furnace pass. Inwardly of the sheets are disposed a plurality of vertical reinforcing structural members or buckstays 54 which extend. from the bottom sheet 56 of the furnace to an upper angle member 58. The buckstays 54 are disposed intermediate the openings 52 but it is obvious that as many buckstays may be employed as is deemed requisite for the strength of the shell, and a greater or lesser number of buckstays may be provided disposed so as not to interfere with` the roller hearth.

In our preferred embodiment the buckstays take the form of structural steel channels having their webs 6U toward the interior" of the furnace and their fianges 62 abutting the sheets 50.

ISISl The dimensions of the individual sheets 58 and the deposition of the buckstays 54 are so chosen that each sheet terminates along an edge of a flange 62 of the buckstay. Referring more particularly to Fig. 8, it may be observed that the two adjacent sheets 58 and 50 have their ends abutting along the ange 62. The purpose of this is to permit the three elements to be securely welded together to form a gas-tight joint and to have the buckstay reinforcing the weld. It is at once obvious that the off-drive-side shell portion can be formed from as many sheets as the length of the furnace requires, and it is equally obvious that the size of these sheets need not necessarily be the same, nor need the spacing between the buckstays be the same. But it is most desirable in our preferred construction that two of the sheets abut along the line corresponding with an end of one of the flanges of a buckstay.

Referring back to Fig. 1, it maybe observed that the buckstays are disposed over the supporting channels I8 so that the entire shell structure is securely supported on the foundation for the furnace. Extending between each buckstay and welded thereto are horizontally-aligned angles 64 which brace the shell portion 28 against forces tending to bow the shell sheets, as for example, the forces due to the pressure of the arch of the top wall 4. These angles 64 extend, as previously indicated, between the individual buck` stays, and to provide additional top-wall-supporting means at the buckstays themselves, smaller angles 86 are secured, as by Welding, to the outside surfaces of the buckstays themselves. The angles 66 are obviously disposed so that their horizontal legs are substantially in a plane with those of the angles 64, and the length of each is substantially equal to the width of the buckstay to which it is attached. The aforesaid angles are disposed at such height as to brace the shell portion 20 most effectively against the pressure vof the arched top wall 4 and their disposition will therefore depend largely on the height of the heating chamber Il?.

The angle members 58 are also welded to the inside of the sheets 50 to form an oil seal for the top shell portion. However, the provision of such a seal is old in the art and it suices to state that the welding of the angle 58 to the sheets 58 must be all oil-tight. It may be observed, however, that'in accordance with our invention the upper end of the buckstays 54 preferably abut the lower surfaces of the angles 58 so that the weld need not be a supporting weld,

but need only assure a leak-proof trough 'I8 for the oil seal. However, we can terminate the upper ends of the buckstays slightly below the angles 58 in furnaces where excessive changes r in dimensions might occur due to high variations in temperatures, and in such instances the weld between the angles 58 and sheets 58 will, of course, be considerably heavier. As was the case with the sheets 5D, as many angles 58are employed as the length of the furnace requires although the individual angles 58 may be considerably longer than the individual sheets 58 since such angles are commercially available.

The different bearings for the olf-drive-side end of the rolls are secured in a gas-tight manner directly to the shell portion 2,0 in any customary manner, but to reinforce the shell portion at the bearing parts thereof, bearing-reinforcing plates 12 are disposed at the level of the hearth between the respective buckstays, and are welded thereto for rigidity. "These plates'l2V have suit# tend through the holes i4 with their heads on the inside of the bearing support and suitably welded in position, certain of such bolts being shown at 16 in Fig. 8. By welding the heads of the bolts completely around their peripheries a fastening means for the ofl-drive-side bearings is provided which is permanently disposed, and is gas-tight. Actually, the holes 14 are drilled while the furnace is being assembled so that an accurate alignment of the bearings can be obtained.

It may be observed that off-driVe-side shell portion 28 has no disguring parts on its outside except for the bearings 28 which are somewhat symmetrically arranged thereon. While appearance is not a serious factor in furnace construction, nevertheless, our construction does yield a substantial shell having a neat appearing outside not marred by structural members. The provi-y sion of buckstays on the inside of the shell, together with the structural members 58, 84 and 66, and the plate 'l2 all serve, in addition to their previously described functions, to stiffen the outer shell portion 28 so that on the whole the shell portion not only encases the furnace wall, but also acts to resist excessive wall pressures. Of course, in the building of a furnace, the bricking and insulation are properly disposed about the inside structural elements of the shell.

The construction of the `drive-side shell portion i8 follows to a large extent the previouslydescribedconstruction of the off-driVe-side shell portion 20 in that a plurality of buckstays 'I8 are disposed in spaced relation along the 'length thereof with their upper ends terminating at the sheets are formed and disposed in order` to provide the channel enclosure for the protruding drive-side ends of the rolls of the roller-hearth.

Referring more particularly to Figs. 2, 3, 4 and 5, which show the drive-side-shell portion, the

channel is represented in its entirety by the ref erence numeral 86, and is formed by an upper sheet portion 88, a lower sheet portion 98 and a vcover plate 92.

In accordance with our invention we depart from the customary practice of forming the driveside shell portion of a single continuous sheet extending from the bottom of the furnace to the top. In our construction we use upper sheets such as 88 bent at 84 to provide an outwardly projecting portion 96 which serves as the top of the channel 88. A second series of sheets such as 98 is provided at the lower .portion of the furnace and also comprises a lower'vertical portion contiguous with the brickwork of the driveside wall 6, but which is bent as at 81 to provide a lower extending portion 98 forming the bottom of the channel 86. The bends 84 and 81 are appropriately vertically spaced from each other a distance determined by the design of the furnace, but sufficient to enable all the necessary driveside appurtenances to be contained within the channel 86. In our preferred form the outer ends of the bent portions B and 98 are turned upwardly and downwardly, respectively, to provide flanges |00 and |02 extending lengthwise of the furnace. These flanges have suitable holes |04 through which extend bolts |06 for securing the cover plates in position.

` For long furnaces, it is, of course, necessary that a plurality of upper and lower sheets be employed as well as a plurality of cover plates. In Figs. 2 and 5 is indicated an abutting joint |08 for the upper sheets and I H3 for the lower sheets, these joints being located at the end of a ange I I2 of a buckstay 'i8 for the reasons explained in the similar construction or" the off-drive-side shell portion 20. The bent portions of abutting ends of the sheets are also welded together by a weld which will ensure a gas-tight structure. In Fig. 5 the reference numeral III indicates a weld between two abutting ends of two upper sheets.

In our preferred construction,'thel cover plate for the channel is formed of a plurality of relatively small sections -so that any one may be readily removed for the purpose of replacing a roll or otherwise repairing parts that may happen to become defective. To the end that the diierent sections |53 of the cover plate may be removably mounted in a gas-tight manner, crossbar plates IIA are provided which are welded to the bent portions 95 and 08 flush with the iianges |00 and |02. These cross-bar plates are relatively narrow and are of a width sumcient to provide two vertically-parallel rows of holes I|6 through which bolts I I3 may extend for securing the plate sections II3, one vertical row serving one cover plate, and the other an adjacent cover plate. In the completed furnace, therefore, each section IIS is securely bolted to the flanges |00 and |02 and to two successive plates II with a gasket interposed to assure a gas-tight seal for the cover plate.

In order to'support the drive-side bearings and also to impart a degree of rigidity to the driveside shell portion, a plurality of plates |22 extend between the bends S4 and 9i and lengthwise of the furnace, these plates preferably being aligned with the upper portions of the sheets 08 and lower portions of sheets .90 that are contiguous with the brick work of the wall, so that the effect of a single sheet is obtained when these plates |22 are welded to the sheets 88 and 90. The plates |22 are, of course, provided with suitable apertures |24 through which the drive-side ends of the rolls may pass, and also to provide a more solid support for the drive-side bearings 21, narrow bars |26 of substantial thickness are welded to the plates |22 on each side of the apertures` |24. However, in order to permit removal of the drive-side bearings, we prefer to drill and tap holes in the bars |26, so that the bearings may be secured thereto in an obvious manner with removable bolts screwing into the tapped holes in l the bars |26.

In accordance with our invention, therefore, we

` have provided a reinforced shell structure which on the'drive-side of the furnace has a' minimum of welding. Perhaps the advantages of our invention can best be understood with reference to Fig. 9 which shows one form of a prior construction. In this figure the drive-side `shell portion comprises, in effect, a single continuous sheet |30 suitably apertured, and extending from the top of the furnace to the bottom. In order to obtain the drive-side channel, structural members in the form of channels |32 and |34 are welded to the' outside surface of the sheet |30, that is, to the side away from the interior of the furnace. This, of course, requires two complete gas-tight welds running substantially the-full length of the furnace, one between the sheet |30 and the member |32, and the second between the sheet |30 and the member |34. Additionally, it has been customary to provide the reinforcing buckstays, or the equivalent for the shell, on the outside of the sheets. Where these buckstays pass through the members |32 and |34, considerable cutting' and tting are required, or, as an alternative, if the buckstays be made of sections with one section terminating on the top of member I 32, a second section terminating at the bottom member I 34, and an intermediate member within the channel aligned with the other two sections, some of the cutting and fitting is eliminated by sectionalizing the buckstays, but nevertheless enough extra effort and welding are required to render our construction a distinct improvement thereover. In any event, the welding of the joints in structures built in accordance with prior practice is not only an expensive item but such welds also frequently develop leaks with continued use of the furnace.

By comparison, our channel structure has no welds whatsoever running lengthwise of the furnace and only occasional welds running the height of the furnace where a plurality of individual sheets must be placed end to end to obtain the full length ofthe furnace. Such welds, however, are also necessary in prior structures. Additionally, because of the bent outwardly projecting bottom portion 98 of our structure, we can provide a trough for any oil draining from the power transmitting means in the channel. For example, the lower section 90 may be centrally bowed or bent downwardly as shown more particularly in Figs. 1 and 3. Any oil in the trough |30 so formed in the bottoms member 98 may be drained from the channel by means of a suitable drain plug indicated schematically at |30, and suitably disposed with respect to the channel to be at the lowermost point thereof.

In furnaces where the differences in temperature between the outer flanges of the channel and that part next to and connected with the furnace wall are sufficiently great to create forces tending to cause a bowing of the channel and wall, it is vdesirable to provide the channel with expansion joints spaced at intervals along the length thereof to prevent bowing of the shell. 'I'hese joints besides providing for expansion must be gastight, and in Figs. 10 to 13, we show one such joint in detail, it being understood, of course, that as many of these joints may be employed as is deemed necessary. Primed and double primed numerals are employed for parts similar to those of the prior gures.

The joint can be formed by cutting a slot |50 in a top bent portion 96 and a similar slot in a bottom bent portion 98 of the channel sheets. The flanges equivalent to |00 and I 02 of the prior figures are also slotted, having a slot preferably somewhat wider than the slot |50. The cutting of the flanges divides them into. portions |00 and |02 to the left of Fig. 10, and |00 and |02 to the right. -Between the anges |00 and |02 and flush with their outsides is Welded a plate II4, and a plate |10" is similarly welded between flanges |00" and |02", the function of these plates being similar to those of plates ||4, differing only in that they are provided with only one liliA set of apertures H6'. The adjacent vertical edges |52 and |54 of the plates H4 and H4, respectively, are spaced from each other so that, in effect, a complete slotted portion is provided in the channel running from the wall at the top of portion 96 horizontally to the outermost part of the channel, then vertically down, and then horizontally back along the bottom portion 98.

The entire slotted portion is covered by a bellows expansion member fabricated into an integral gas-tight piece shaped to the cross-section of the channel, and indicated in its entirety by the reference numeral |56. The member |56 is generally U-shaped in cross-section, and comprises two flat legs |58 and |60 with a bellows |62 therebetween. The legs are welded gas-tight to the portions 96 and 98 and to the plates ||4' and H4, so that the expansion member |56 straddles the slotted portion of the channel, the enlarged cut in the flanges permitting the expansion member to t the channel closely. The resulting structure is a gas-tight channel provided with a suitable expansion means.

A cover 92 fastens to the flanges |00 and |02' at the left of the expansion joint of Fig. 10,.and to the plate H4 with a gasket |20 interposed to assure a tight joint, While the cover 92" is similarly secured on the right, being, however, fastened to the plate |4" and the flanges |00" and |02", with a gasket |20" interposed.

While we have shown our invention in the form which we now believe to be the best embodiment thereof, it is obvious that many changes and variations may be made in the specific details described, and it is obvious vthat our invention is also applicable to other types of furnaces. Accordingly, it is desired that the appended claims be given their broadest interpretation and that they be limited only by the prior art.

We claim as our invention:

l. A furnace of the roller-hearth-type having a side wall with 4spaced openings therein through which the ends of the rolls of the hearth can protrude, and an outer metallic shell for said wall, said shell comprising metal sheets, certain of said sheets being bent with a bend somewhat above said openings, and with portions extending upwardly from said bend contiguous with said wall and other portions extending outwardly from said lbend, and otherfof said sheets also being bent with a bend somewhat below said openings, and with portions extending downwardly from the last said bend contiguous with said wall, and other portions extending outwardly from the last said bend.

2. A furnace of the roller-hearth type having a side wall with spaced openings therein through which the ends of the rolls of the hearth can protrude, and an outer metallic shell for said wall, said shell comprising metal sheets, certain of said sheets being bent with a bend somewhat above said openings, and with portions extending upwardly from said bend contiguous with said wall and other portions extending outwardly from said bend, other of said sheets also being bent with a bend somewhat below said openings, and with portions extending downwardly from the last said bend contiguous with said wall and other portions extending outwardly from the last said bend, and means including removable covers across said outwardly-extending portions forming therewith, in effect, a gas-tight longitudinal channel for encasing the protruding ends vof the rolls.

75; 3. A furnace of the roller-hearth type having a side wall with spaced openings therein through which the ends of the rolls of the hearth can protrude, and an outer metallic shell for said wall,

said shell comprising metal sheets, certain of said y sheets being bent with a bend somewhat above said openings, and with portions extending upwardly from said bend contiguous with said wall and other portions extending outwardly from said bend, other of said sheets also being bent with a bend somewhat below said openings, and with portions extending downwardly from the last said bend contiguous with said wall and other portions extending outwardly fro-m the last said bend, said outwardly-extending portions being further bent at their edges to form flanges, and a cover plate means cooperating with said flanges to form therewith, in effect, a longitudinal channel for encasing the said ends oi the rolls.

4. A furnace of the roller-hearth type having a side wall with spaced openings therein through which the ends of the rolls of the hearth can protrude, and an outer metallic shell for said wall, said shell comprising metal sheets, certain of said sheets being' bent with a bend somewhat above said openings, and with portions extending upwardly from said bend contiguous with said wall and other portions extending outwardly from said bend, other of said sheets also being bent with a bend somewhat below said openings, and with portions extending downwardly from, the last said bend contiguous with said wall and other portions extending outwardly from the last said bend, and plates extending across the space between said upper and lower bends, and having openings aligned with the said openings in said side Wall.

5. A furnace ofthe roller-hearth type having a side wall with spaced openings therein through which the ends of the rolls of the hearth` can protrude, and an outer metallic shell for said wall, said shell comprising metal sheets, certain of said sheets being bent with abend somewhat above said openings, and with portions extending upwardly from said bend contiguous with said wall and other portions extending outwardly from said bend, other of said sheets also being bent with a bend somewhat below said openings, and with portions extending downwardly from the last said bend contiguous with said wall and other portions extending outwardly from rthe last said bend, plates extending across the space between said upper and lower bends, and having openings aligned with the said openings in saidside wall, and roll-bearing means secured to said plates.

6. A furnace of the roller-hearth type having a side wall with spaced openings therein through which the ends of the rolls of the hearth can protrude, and an outer metallic shell for said wall,

l said shell comprising metal sheets, certain of said aligned with the said openings in said side wall,

and means including removable covers across said outwardly-extending portions forming therewith,

inefect, a gas-tight channel for encasing the protruding ends of the rolls. '7. A furnace of the roller-hearth type having a side wall with spaced openings therein through which the ends of the rolls of the hearth can protrude, and an outer metallic shell for said wall, said shell comprising metal sheets, certain ofA said sheets being bent with a bend somewhat above said openings, and with portions extending upwardly from said bend contiguous with said wall and other portions extending outwardly from said bend, other of said sheets also being bent with a bend-somewhat below said openings, and with portions extending .downwardly from the last said bend contiguous with said wall and other portions extending outwardly from the last said bend, plates extending across the space between said upper and lower bends, and having openings aligned with the said openings in said side wall, roll bearing means secured to said plates, and means including removable covers across said outwardly-extending portions forming therewith, in eifect, a gas-tight channel for encasing the protruding ends of the rolls.

8. The structure of claim `1 characterized by said lower outwardly extending portion being shaped to provide a trough.

9. The structure of claim 2 characterized by said lower outwardly extending portion being shaped to provide a trough.

l0. A furnace of the roller-hearth type having walls, an outer shell for said walls, a roller-hearth comprising a plurality of rolls, two opposite of said Walls having aligned, spaced openings through which the ends of said rolls pass, the said ends of said rolls projecting beyond said walls, said shell comprising metal sheets for one of the last two said walls, certain of said sheets having a portion contiguous with the last said wall above said openings and a bent portion projecting outwardly of the last said wall, other of said sheets having a portion contiguous with the last said wall below said openings and a bent portion projecting outwardly of the last said wall, means including removable covers across said bent portions forming therewith, in effect, a channel encasing the said ends of said rolls that projected beyond the last said wall, bearing means in said channel for supporting saidrolls at one end, and bearing means for supporting the said rolls at the other end. l

11. A furnace of the roller-hearth type having walls, an outer shell for said walls, a roller-hearth comprising a plurality of rolls, two opposite of said walls having aligned, spaced openings through which the ends of said rolls pass, the said ends of said rolls 'projecting beyond said walls, said shell comprising metal sheets for one of the last two said walls, certain of said sheets having a portion contiguous with the last said wall above 'said openings and a bent portion projecting outwardly of the last said wall, other of said sheets having a portion contiguous with the last said wall below said openings and a bent portion projecting outwardly of the last vsaid wall, means including removable covers across said bent portions forming therewith, in effect, a channel encasing the said ends of said rolls that projected beyond the last said wall, bearing means in said channel for supporting said rolls at one end, bearing means for supporting the said rolls at the other end, and driving means for said rolls including power transmitting means in said channel.

12. 'I'he structure of claim l1 characterized by the said lower bent portion being shaped to provide a trough.

13. A furnace of the roller-hearth type having walls, an outer shell for said walls, a roller-hearth comprising a plurality of rolls, spaced openings through one of said walls and through which the ends of said rolls pass, the said ends of said rolls projecting beyond said wall, said shell comprising metal sheets for the last said wall, certain of said sheets having a portion contiguous with the last said wall above said openings and a bent portion projecting outwardly of. the last said wall, other of said sheets havinga portion contiguous with the last said wall belowsaid openings and a bent portion projecting outwardly of the last said Wall, both said bent portions extending beyond the said projecting ends of said rolls, cross-bar plates across the said bent portions approximately flush with their outermost ends, and in spaced relation, and removable means secured to said bent portions and said cross-bar plates forming therewith, in effect, a channel encasing the ends of said rolls that project through the last said wall.

14. A furnace of the roller-hearth type having walls, an outer metallic shell for said walls, a roller-hearth comprising a plurality of rolls, one of said walls having aligned, spaced openings through which similarly disposed ends of. said rolls pass, the said ends projecting beyond said wall, said shell including a channel encompassing said projecting ends, said shell comprising a metal sheet bent at substantially a right angle with one side contiguous with the last said wall and the other forming a part of said channel.

l5. A furnace including walls, an outer metallic shell having an inside surface contiguous with said walls, and spaced vertical structural iron members, said shell being welded to the said members on the inside surface of said shell whereby the said members are, in effect, embedded in said walls, said iron members reinforcing said shell; and supporting means for said furnace including supports under said iron members. n

16. A furnace including vertically-disposed walls, an outer metallic shell having an inside surface contiguous with said walls, a foundation for supporting said furnace and comprising structural iron beams under said walls, and a plurality of spaced, substantially vertical buckstays in the form of channels having flange members, said buckstays supported by said beams, and the ends of said flanges and the said inside surface o f said shell being welded whereby the buckstays are, in eect, embedded in said walls.

17. A furnace including vertically-disposed walls, an outer metallic shell having an inside surface contiguous with said walls, a foundation for supporting said furnace and comprising structural iron beams under said walls, a plurality of spaced, substantially vertical buckstays in the form of channels having flange members, said buckstays supported by said beams, and the ends of said flanges and the said inside surface of said shell being welded whereby the buckstays are, in effect, embedded in said walls, and stiffening members secured to the upper portion of said shell between -said buckstays.

18. A furnace of the roller-hearth type having vertically-disposed walls, a roller-hearth comprising a plurality of rolls with ends projecting through spaced openings in certain of said walls, an outer shell for said walls, said shell for one of said walls through which the said rolls project comprising metal sheets, certain of said sheets having. an upper portion with an inside surface contiguous with the last said wall above its openings and a bent portion projecting. outwardly of the last said wall, other of said sheets having a lower portion with an inside surface contiguous with the last said wall below its openingsand a bent portion projecting outwardly of. the last said wall, the extremities of said bent portions being formed with anges, cover plateA means secured to said flanges, to forni, in effect, a gas-tight channel, a plurality of vertically disposed buckstays, said sheets and buckstays being welded on the said inside surfaces, said buckstays being disposed intermediate certain of said openings, and plates contiguous with the last said wall and extending between said lower and upper portions of said sheets, said plates being secured in position and having openings aligned with the openings in the last said wall.

19. A furnace of the roller-hearth type having vertically-disposed walls, a roller-hearth comprising a plurality of rolls with ends projecting through spaced openings in certain of. said walls, an outer shell for said walls, said shell for one of said walls through which the said rolls project comprising metal sheets, certain of said sheets having an upper portion with an inside surface' contiguous with the last said Wall above its openings and a bent portion projecting outwardly of the last said wall, other of said sheets having a lower portion with an inside surface contiguous with the last said wall below its openings and a bent portion projecting outwardly of the last said wall, the extremities of said bent portions being formed with flanges, cover plate means secured to said flanges, to form, in eii'ect, a gas-tight channel, a plurality of vertically disposed buckstays, said sheets andbuckstays being welded on the said inside surfaces, said buckstays being disposed intermediate certain of said openings, plates contiguous with the last said wall and extending between said lower and upper portions of said sheets, said plates being secured in position and having openings aligned with the openings in the last said wall, bearing means for said rolls secured to said plates, and driving means for said rolls including power transmitting means in said channel.

20. The structure of claim 19 in which the lower bent portions are shaped to provide a trough. y l

21. The structure of claim 2 including transversely-directed expansion joints in said channel whereby forces due to diii'erences in temperature between the said sheet portions contiguous with the wall and the channel do not tend to buckle the said shell.

22. The structure of claim 3 including transversely-directed expansion joints in said channel whereby forces due to differences intemperature between the said sheetvportions contiguous with the wall and the channel do not tend to buckle the said shell.

23. The structure of claim 13, in which said bentportions are provided with vertically aligned slots, and certain of said plates are disposed one on each side of said slots, and an expansion member is welded to said flanges and plates, and coveringsaid slot. 4

24. A furnace of the roller-hearth type, having walls, an outer metallic shell for said walls, one of said walls having aligned, spaced openings through which similarly disposed ends of said rolls pass, the said ends projecting beyond said 1 wall, said shell including a longitudinal channel encompassing s aid ends, said channel including transversely-directed expansion joints whereby forces due to dilferences in temperature between the part of said shell that is contiguous to the wall, and the part of, said channel away from the` 26. Alroller-hearth heat-treatment furnace of the type described including refractory and insulating walls, an outer metallic shell. having an l inside surface contiguous with said walls, spaced vertical structural members for reinforcing said shell, said shell having its inside surface secured to said members, said walls and shell including openings through which ends of the rolls of the roller-hearth protrude, said shell vincluding a channel on the outside thereof for encompassing the ends ofthe rolls.

FREDERICK R. J. DAVIS. GERHARD P. massMANN.v 

